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Core removal. Howard Pickard LBBC Technologies. Core removal. LBBC Technologies Suppliers of autoclave systems. Dewaxing Boilerclave TM. Core Leaching autoclave. Core removal. LBBC Technologies Suppliers of autoclave systems with Quicklock TM doors. Independent family owned

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core removal
Core removal

Howard Pickard

LBBC Technologies

core removal2
Core removal

LBBC Technologies

Suppliers of autoclave systems

Dewaxing BoilerclaveTM

Core Leaching autoclave

core removal3
Core removal

LBBC Technologies

Suppliers of autoclave systems with QuicklockTM doors

Independent family owned

Established over 130 years

Variety of autoclave applications

Equipment development

Service and support

shell vs core removal
Shell vs Core removal
  • Removal of the shell involves…
  • Removal of a core involves…
  • metal shrinkage assists the process
  • large ceramic particles
  • mechanical methods
  • small ceramic particles
  • complex geometry
  • enclosed areas
cores

Used by a minority of foundries

Increases applications for investment castings

Implications throughout process

Removal perceived to be the hardest stage

Considering only Silica based cores

Cores
removal of core key issues
Removal of coreKey issues
  • Geometry
    • Is it possible to remove?
  • Metal Alloy
    • Susceptible to attack
  • Cost
    • Market potential, capital investment
  • Health & Safety
    • Exposure of operators, waste by-products
  • Environment
    • By-products of the process
removal of core methods
Removal of coremethods
  • Hydraulic cleaning
  • Sand blasting
  • Caustic bath / mechanical agitation
  • Caustic autoclave
  • Molten caustic
  • Ultrasonics
removal of core methods9
Removal of coremethods
  • Hydraulic cleaning
  • Sand blasting
  • Caustic bath / mechanical agitation
  • Caustic autoclave
  • Molten caustic
  • Ultrasonics

Description

High pressure water jets erode core particles then recirculate within machine

Advantages

Good method for simple core geometry. Low health and safety issues.

Disadvantages

Can be difficult and time consuming to remove the core.

  • Best practice
  • Large non complex cores
removal of core methods10
Removal of coremethods
  • Hydraulic cleaning
  • Sand blasting
  • Caustic bath / mechanical agitation
  • Caustic autoclave
  • Molten caustic
  • Ultrasonics

Description

Grit or shot is fired at the core passage within a cabinet either by compressed air or an impeller.

Advantages

Effective at removing large cores with low complexity. Low health and safety issues. Good casting finish

Disadvantages

High level of dust. High possibility of casting wear.

  • Best practice
  • Grade of shot/grit.
  • Mechanical separation
removal of core methods11
Removal of coremethods
  • Hydraulic cleaning
  • Sand blasting
  • Caustic bath / mechanical agitation
  • Caustic autoclave
  • Molten caustic
  • Ultrasonics

Description

Sodium or potassium hydroxide solution (35 – 50%) in a tank at room or elevated temperature. Parts placed into solution and left for liquid to break down the core material. Mechanical or air agitation may be added.

Advantages

Low cost, simple method for removing cores. Minimises erosion of casting.

Disadvantages

Can take long time for large or complex cores. High level of health, safety and environmental risks

  • Best practice
  • Consider agitation
  • Automate systems
  • Drill holes first
removal of core methods12
Removal of coremethods
  • Hydraulic cleaning
  • Sand blasting
  • Caustic bath / mechanical agitation
  • Caustic autoclave
  • Molten caustic
  • Ultrasonics
core examples
Core examples

Courtesy of Certech

slide15

The process

The

Equipment

slide16

The process

Load

Baskets

slide17

Typically

120 psi

160 oC

NaOH 20%

KOH 40%

Fill &

Cycle

The process

core leaching autoclave20
Core leaching autoclave
  • Best practice
  • NaOH or KOH
    • Speed, recycle
  • Concentration
    • High / low, temperature
  • Component orientation
    • Up or down, horizontal
  • Cycle parameters
    • Dwell, vent, mid way break
  • Recycle caustic
    • Cost, efficiency
  • Post leach operations
    • Water wash
removal of core methods21
Removal of coremethods
  • Hydraulic cleaning
  • Sand blasting
  • Caustic bath / mechanical agitation
  • Caustic autoclave
  • Molten caustic
  • Ultrasonics

Description

Bath of molten concentrated caustic. Castings placed inside

Advantages

Quick and effective at removing cores

Disadvantages

Many health and safety issues. Likely to attack the casting alloy surface

  • Best practice
  • Take great care
  • Check suitability of alloy
removal of core methods22
Removal of coremethods
  • Hydraulic cleaning
  • Sand blasting
  • Caustic bath / mechanical agitation
  • Caustic autoclave
  • Molten caustic
  • Ultrasonics

Description

Use of ultrasonic rays to break down macroscopic structures

  • Best practice
  • Research phase – no commercial system

Advantages

Speeds up the process

Non contact

Disadvantages

Early development of the process. Untested.

slide23

Removal of core

Consider the key issues

Be aware of the alternative methods

Review the operation

Increase application of investment castings

Increase yield

Improve quality

shell and core removal
Shell and Core removal

Special thanks to :

Dr Brian Robson

Casting Solutions Limited

Email : brianrobson@live.com

  • References
  • Fettling and finishing, Dr Alan Clegg, EICF workshop 2004
  • Leaching of preformed ceramic cores, Miller & Eppink, Sherwood Refractories, ICI 1983